This type of door is intended to be placed around a bay formed through a wall for the purpose of opening or closing the bay. Closing is performed by a curtain which is capable of moving down between the uprights or of being raised to be collected at the top beneath the cross-member, or within the cross-member, or to one side thereof. The curtains may be in the form of a flexible sheet or in the form of rigid panels that are hinged to one another, with the curtain being reinforced by horizontal bars which may also serve as hinges and whose ends slide for guidance purposes in slideways that are formed by the uprights, or that are disposed in the uprights. While a curtain is being raised, it may be wound up inside the cross-member or it may be folded up concertina-like beneath the cross-member, or it may be offset laterally between guide rails. The cross-member is generally a channel section member whose opening faces downwards. The mechanical units for actuating and controlling operation of the door are placed inside the cross-member, e.g. a shaft onto which the curtain or lifting straps are wound, an electric motor, an end-of-stroke contact, etc.
It is important for these doors to be sealed at the top, particularly when the curtain is down in its closed position. That is why the top end of the curtain is placed as high as possible inside the cross-member, and when the top end of the curtain is stationary it is fixed to the web of the top cross-member.
However, another requirement is to have access to the mechanism for maintenance and repair. If the top portion of the curtain is placed as high as possible inside the cross-member, then it masks the mechanism so that it can be accessed from one side only, thereby limiting the conditions in which such doors can be installed.
An object of the invention is to provide a removable sealing device for a raisable-curtain industrial door enabling easy access to the mechanism of the door under all conditions and ensuring that the fixed portion of the door is sealed under all conditions, in particular when the door is closed.